Modern theater motion picture projectors are assembled from several different component parts. These parts include a projection head, a light source, a sound head and a film supply and take-up transport system. Film from a supply coil in the transport system is intermittently advanced past an aperture in the projection head, past the sound head and returned to a take-up coil in the transport system. Various types of film transports have been used, with the most common type including a film supply reel and a film take-up reel. The projection head pulls film from the supply reel at a rate required for normal projection, and the take-up reel is driven to Wind up the film after it leaves the projection head and the sound head. In some cases, the film is drawn from the center of the supply reel.
In recent years, there have been several proposals for designing the projection systems to handle longer films. This is particularly necessary in the case of the new large format films, such as 70 mm or the like. Examples of such projection systems are disclosed in various U.S. Patents such as U.S. Pat. No. 4,169,566, 4,010,910, 3,823,890 and the like. For example, the U.S. Pat. No. 4,169,566 patent, the disclosure of which is incorporated herein by reference, discloses a platter-type film transport system which includes a single unidirectional motor which drives a vertical shaft and two or more bearing plates attached to a shaft driven by the motor. A separate platter rests on each bearing plate. The platters are each free to turn on the bearing plate independently. One of the platters functions as a film source or supply and carries a coil of the film. The film is removed from the center of the coil and is delivered to the projector. As the film is removed from the center of the coil, the size of the innermost film loop is sensed for controlling an auxiliary motor which either slows the platter to a speed below the speed of the driven shaft or accelerates the platter to a speed above that of the driven shaft. Film from the projector is collected on a second or take-up platter. A circular core is attached concentrically to the film take-up platter. When the core is attached to the platter, a locking mechanism connects the platter to the bearing plate. Film from the projector passes over a dancer arm which is positioned according to film tension and is wound on the core of the take-up platter.
Devices such as the just-discussed platter system have improved the efficiency with which motion picture films are displayed, and it is now possible to show movies of great length without the need of a projectionist. Thus, while in the past, a feature length film may have been shipped to the theater in several portions each of which were, for example, twenty to thirty minutes in length, with a projectionist changing reels as necessary, it is now possible for a feature length film to be shipped in portions that far exceed the twenty to thirty minutes lengths, and can even be shipped as a single length film. A projectionist may not even be necessary in such situations. The efficiency with which a film is now displayed is thus considerably increased.
While such advances in efficiency are important and have been extremely beneficial to the film industry, the increased length of films on a single reel has produced a problem that the art has not recognized. This problem is associated with the changing of a portion of the film. That is, for example, if a movie theater is changing feature films, the initial portion of the program which includes advertisements, announcements, coming attractions and the like should also be changed to be commensurate with the new feature film. It is also highly likely that a plurality of changes will be made to such "trailers" each week, even if the feature remains unchanged.
However, due to the great length of modern films as shipped to the theater, it will be extremely difficult to change such initial portion. It is impractical to run the entire film to this initial portion, orient the film so a new initial portion can be inserted into the program, and then re-orient the entire program to be in condition for display as a whole from the beginning.
This problem is exacerbated by devices such as the aforementioned center-feeding platter-type film transport system which draw the film from the center of the reel. In such cases, the portion of the film that is to be changed is at the most inaccessible location of the overall reel, the center. This makes it even more difficult to effect a change.
The just-mentioned problems associated with changing a portion of a film are present with all films, but are greatly exaggerated in the cases of films having the large formats, such as the 70 mm films, that can be quite heavy and difficult to handle.
Accordingly, there is a need for a means and a method which permit the long modern films to have a portion thereof changed in an expeditious manner. There is a further need for such a means and method which can be used in conjunction with a center-feed film transport system.